Recent dash light disco electrical mayhem from the Starlet served as a reminder that an automotive electrical system can go haywire at any time. An automobile electrical system comprises three key parts. The battery stores electricity to spin the starter and start the engine. The alternator produces electricity once the engine is running by way of an engine driven belt. The voltage regulator balances the delivery of electrical power between the battery, spark plugs, and hi-fi stereo playing Burt Bacharach. This balance of power will come apart when any one of these three components fail. Starters that click rather than spin and dead batteries can be the result of a spent alternator or fussy voltage regulator.

Fully Cooked

Classic symptoms of a dead or dying alternator are increasingly dim headlights or sluggish electrical accessories after dark. The morning after may bring nothing but a sad click from the starter. A vehicle driven around long enough with a spent alternator will eventually exhaust the battery. The battery only has so much stored power. Everything will come to a halt. This usually occurs at night while driving with the hi-beams, heater, and MC5 at full blast. Stranded at night with a dead car is not the world's best motoring experience.

Electrical Gremlins

The paradox of alternator replacement is that automotive electrical gremlins can be tricky devils. Check each part and the charging system as a whole before replacing components such as the alternator. Removing and replacing the alternator only to find out that the voltage regulator, battery, or a loose wire is the faulty party can be an expensive lesson. Your local auto parts store may now have portable diagnostic equipment that can be wheeled out to sniff out problems with the charging system. A service manual and multimeter go far in outlining test procedures for checking the charging system and components with a multimeter. Check alternator output itself. Check Voltage delivery at the battery. Check voltage regulator output.

Remove and Replace

If the alternator has gone permanently south, replacing it is usually a relatively easy job. We say usually for a reason. Sometimes alternators can be held captive by other components at the core of what amounts to an automotive Gordian knot. If you can't see the alternator from above or below the engine then there may be trouble in replacement. This is where a service manual comes in handy for specific procedures. The following tips are general guidelines. Jacking up the car or putting it up on ramps may be required to get to the alternator.


Stuff You'll Need:

· A service manual outlining vehicle specific charging system tests and alternator replacement procedures for your 1972 Dodge Dart Swinger, or similar.
· A multimeter
· Wrenches and basic hand tools
· A replacement alternator
· A replacement belt
· Another car or pal to drive back to the auto parts store after they give you the wrong alternator.


Check the charging system and individual components before deciding the alternator is at fault for electrical gremlins. External voltage regulators may have seen a few presidents. Most modern vehicles have solid-state internal voltage regulators inside the alternator itself.

Turn off the engine. Disconnect the battery negative and positive. A wrench or a screwdriver across alternator connections and a ground can cook components like engine control computers and hi-fi sound systems. Never disconnect electrical while the engine is running.


V-belt equipped vehicles usually have two bolts holding an alternator in one place. One bolt or assembly holds belt tension. The other bolt holds the alternator to its mount. First loosen and remove the tension bolt or assembly. Next loosen the pivot bolt. Push the alternator on its pivot for belt slack.


On more modern vehicles the alternator and engine driven accessories are turned by one serpentine belt. A spring-loaded self-tensioner holds the serpentine belt tight and keeps things spinning. A wrench and pull on the self-tensioner provides belt slack, and allows removal of the alternator.

Remove electrical connections. Remove the pivot bolt. Remove the alternator. Now is a good time to check and replace worn belts.


Compare the old and new alternators to make sure everything is the same. Transfer any nuts or miscellany from the old to new. Reverse the removal procedure to install the new alternator. Go only finger tight on the bolts.


The trick with older v-belt setups is to hold the alternator against the belt and tighten the tension bolt at the same time. Tensioner assemblies may take care of this feat with a few turns of the wrench. Check belt tension. A little under an inch of deflection is ideal. Too much tension will quickly destroy alternator bearings. Better a slightly loose belt than one too tight. Fully tighten pivot bolt only after belt tension is set.

The last step is to start vehicle and check alternator output with a multimeter. Check voltage output at the battery. Run engine for about 15 minutes or so and recheck belt tension. Adjust tension if required. Check belt tension again after about 500 miles.


And You Will Know Us by the Trail of Parts [Internal]